Optical information recording medium, reproducing device for optical information recording medium, control method and control program for the reproducing device, and medium with the control program recorded therein

ABSTRACT

A super-resolution medium ( 1 ) has a medium identification information for specifying a type of medium recorded in a medium information area ( 3 ) by use of pre-pits having a length not shorter than a length of a resolution limit of an optical system in a reproducing device ( 10 ).

TECHNICAL FIELD

The present invention relates to an optical information recording mediumin which information is to be recorded, a reproducing device for theoptical information recording medium, a control method and a controlprogram for the reproducing device, and a recording medium with thecontrol program recorded therein.

BACKGROUND ART

Recently, in order to process a massive amount of information such asimages, enhancement in information density has been sought for inrecording and reproduction of an optical information recording medium.In view of this, super-resolution techniques have been proposed, whichrecord and reproduce information by use of recording marks, or pre-pitsthat are formed by concave portions and/or protrusions, each of whichlengths of the marks or the pre-pits are shorter than a resolution limitof an optical system in a reproducing device. In the description, anoptical information recording medium which is reproducible by thesuper-resolution technique is referred to as a “super-resolution medium”or a “super-resolution optical information recording medium”, whereas anoptical information recording medium which cannot utilize thesuper-resolution technique, that is, an optical information recordingmedium which records information by use of recording marks or pre-pits,each of which have a length longer than a resolution limit of an opticalsystem in a reproducing device, is referred to as a “regular medium” ora “regular optical information recording medium”. The resolution limitof an optical system is determined based on a wavelength of areproduction laser and a numerical aperture of an optical system.

Optical information recording mediums disclosed in Patent Documents 1through 3 are examples of the super-resolution medium.

A rewritable super-resolution medium described in Patent Document 1provides a recording layer and a reproduction layer. The recording layerhas information recorded thereon in a perpendicular magnetizingdirection, and the reproduction layer is provided on the recordinglayer. Reproduction of the information is carried out by havingreproduction laser light irradiated to the reproduction layer.Irradiation of the reproduction laser light to the reproduction layercauses a laser spot to generate. The laser spot thus generated has alight intensity distribution, whereby a temperature distribution isinduced in the laser spot. A magnetic field of the recording layer istransferred to the reproduction layer, to just parts of the laser spothaving a high temperature. This allows reproduction of a signal having ashorter marking length than the resolution limit of the optical system.

In a super-resolution medium described in Patent Document 2, athermochromic pigment layer is provided as a mask layer on a surface ofa reflection layer on which reproduction light is incident thereon. Thethermochromic pigment layer changes in optical characteristic such astransmittance, depending on temperature. The mask layer is a layer whichcauses a super-resolution phenomenon, such as reducing a size of a laserspot in a pseudo manner. Distribution of transmittance is generated dueto a temperature distribution induced by a light intensity distributionin the laser spot on the reproduction layer, near a surface of thereproduction layer on which the reproduction light is incident thereon.For example, when a material which improves in transmittance along withan increase in temperature is used as the reproduction layer,transmittance is improved in just parts having a high temperature,thereby causing the laser spot generated on the surface of thereflection layer to be reduced in a pseudo manner. This allowsreproduction of a signal having a shorter marking length than theresolution limit of the optical system. The technique disclosed inPatent Document 2 is applicable not only to a rewritable opticalinformation recording medium, but also to an optical informationrecording medium only for reproduction.

Furthermore, in a super-resolution medium described in Patent Document3, information is recorded on a substrate by use of concave portionsand/or protrusions. The substrate has a film layer, called a functionallayer, which is made of a thin metal film or the like, provided thereon.Although substantially none of the theory of this super-resolutionmedium is currently known, it is known that signals which have a shortermarking length than the resolution limit of the optical system arereproducible due to a temperature change in the functional layer.

[Patent Document 1]

-   Japanese Unexamined Patent Publication, Tokukaihei, No. 8-180486    (published Jul. 12, 1996)

[Patent Document 2]

-   Japanese Unexamined Patent Publication, Tokukai, No. 2001-35012    (published Feb. 9, 2001)

[Patent Document 3]

-   Japanese Unexamined Patent Publication, Tokukai, No. 2001-250274    (published Sep. 14, 2001)

The following description explains a conventional regular medium 61 anda conceivable super-resolution medium 71, with reference to FIGS. 14through 18.

FIG. 15 illustrates an outer appearance of the conventional regularmedium 61. The regular medium 61 includes a data area 62, and a mediuminformation area 63. The data area 62 is to be recorded with informationto be used by a user. The medium information area 63 is recorded withinformation concerning the regular medium 61. The data area 62 and themedium information area 63 are arranged so that the medium informationarea 63 is provided at an innermost circumferential section and anoutermost circumferential section of the regular medium 61, and the dataarea 62 is provided therebetween, as illustrated in FIG. 15. One exampleof the information recorded in the medium information area 63 concerningthe regular medium 61 is medium identification information, whichindicates itself as a regular medium.

FIG. 14 illustrates an enlarged view of section b shown in FIG. 15. Thedata area 62 and the medium information area 63 are recorded withrespective information by use of pre-pits that are formed by concaveportions and/or protrusions and that are longer than a resolution limitof an optical system in a reproducing device.

The following description explains the conceivable super-resolutionmedium 71. FIG. 17 illustrates an outer appearance of thesuper-resolution medium 71. The super-resolution medium 71 has a dataarea 72 and a medium information area 73. The data area 72 is recordedwith information to be used by a user. The medium information area 73 isrecorded with information concerning the super-resolution medium 71. Thedata area 72 and the medium information area 73 are arranged so that themedium information area 73 is provided at an innermost circumferentialsection and at an outermost circumferential section of thesuper-resolution medium 71, and the data area 72 is providedtherebetween. One example of the information recorded in the mediuminformation area 73 concerning the super-resolution medium 71 is mediumidentification information, which indicates itself as a super-resolutionmedium.

FIG. 18 illustrates a cross sectional view of the super-resolutionmedium 71. The super-resolution medium 71 includes a substrate 74, and areflection, layer 75 and a super-resolution reproduction layer 76layered on the substrate 74 in this order by sputtering. Thesuper-resolution reproduction layer 76 causes a super-resolutionphenomenon to occur. Furthermore, a transparent cover layer 77 isprovided on the super-resolution reproduction layer 76.

FIG. 16 illustrates an enlarged view of section c shown in FIG. 17. Thedata area 72 and the medium information area 73 is recorded withrespective information by use of pre-pits that are formed by concaveportions and/or protrusions and that are shorter than a resolution limitof an optical system in a reproducing device. As such, in thesuper-resolution medium 71, information is recorded by a combination ofpre-pits having a length shorter than the pre-pits of the regular medium61. This allows high density recording of information, thereby allowingrecording of more information.

With the super-resolution medium described in Patent Documents 1 and 2,the greater the power of the reproduction laser, the steeper thetemperature distribution in the laser spot, thereby resulting in anenhancement in super-resolution effect. Even with the super-resolutionmedium described in Patent Document 3, although the cause is notunderstood, the super-resolution effect is enhanced, with greaterreproduction laser power, as similar to the super-resolution mediumsdescribed in Patent Documents 1 and 2. Therefore, reproduction laserpower optimum for reproducing the super-resolution medium 71 is greaterthan reproduction laser power optimum for reproducing the regular medium61.

As described above, recording density of the super-resolution medium 71is higher than recording density of the regular medium 61. Therefore, areproduction clock width optimum for reproducing the super-resolutionmedium 71 is narrower than a reproduction clock width optimum for theregular medium 61.

The following considers a reproducing device having compatibility withboth the regular medium 61 and the super-resolution medium 71, thereproducing device being capable of reproducing both mediums.

In order to reproduce the regular medium 61 and the super-resolutionmedium 71 at their most optimum state by the reproducing device, it isrequired to switch the reproduction laser power and a reproduction clock(this is because the reproduction laser power and the reproduction clockof each of the regular medium 61 and the super-resolution medium 71 aredifferent, as described above). In order to do so, it is required toidentify whether a medium is the regular medium 61 or thesuper-resolution medium 71. Such identification requires to reproduce(i) the medium identification information recorded in the mediuminformation area 63 and (ii) the medium identification informationrecorded in the medium information area 73.

The identification of the medium is desirably carried out by using thereproduction laser power for the regular medium 61, in order to preventincrease in electricity consumption and breakage of the regular medium61 caused by the high reproduction laser power for the super-resolutionmedium 71. However, in such a case, the medium identificationinformation in the super-resolution medium 71 may not be reproducible,thereby causing a problem that no identification can be carried out.

It is an option that in the case the identification could not be carriedout by using the reproduction laser power for the regular medium 61, theoptical information recording medium to be identified is determined asthe super-resolution medium 71, and accordingly the reproduction laserpower and the reproduction clock are switched to the appropriate ones.However, excessive time is required since the switching of thereproduction laser power is carried out after the determination is made.As a result, a long time is required to start-up the reproducing device.Furthermore, even in a case where reproduction could not be carried outdue to some kind of cause even if the optical information recordingmedium to be identified is the regular medium 61, the reproducing devicemistakenly determines that the regular medium 61 is the super-resolutionmedium 71. In response to this determination, the reproduction laserpower is switched from the reproduction laser power for the regularmedium to the reproduction laser power for the super-resolution medium71. As a result, this may cause a breakage problem of the regular medium61. The start-up time of the reproducing device denotes a time periodrequired to carry out a series of processes from arranging the opticalinformation recording medium in the reproducing device to reproducing adata area of the optical information recording medium.

For simplification, the above description is described by limiting itemswhich the medium identification information can identify to a regularmedium and a super-resolution medium, however it is not limited to this.For example, conventionally, the medium identification information isused for identifying a type of a medium (e.g. CD, DVD, BD) and a form ofa medium (e.g. R, RE, ROM).

DISCLOSURE OF INVENTION

The present invention is made in view of the problems, and an objectthereof is to realize (i) a super-resolution optical informationrecording medium, which can be identified as a super-resolution opticalinformation recording medium by use of reproduction laser power for aregular optical information recording medium, and (ii) an opticalinformation recording medium reproducing device capable of reproducingboth the super-resolution optical information recording medium and theregular optical information recording medium.

In the following description, a reproducing device denotes a reproducingdevice according to the present invention, capable of reproducing both asuper-resolution optical information recording medium according to thepresent invention and a regular optical information recording medium.

In order to attain the object, a super-resolution optical informationrecording medium according to the present invention includes: a firstarea in which a content is to be recorded by forming recording marks,one or more of the recording marks being shorter than a length of aresolution limit of an optical system in a reproducing device; and asecond area in which medium identification information for specifying atype of the medium is recorded by use of pre-pits that are formed byconcave portions and/or protrusions, the pre-pits which form the mediumidentification information being not shorter than the resolution limitof the optical system.

According to the arrangement, medium identification information of arecordable/reproducible super-resolution optical information recordingmedium according to the present invention is recorded by use of pre-pitsthat are formed by concave portions and/or protrusions and that are notshorter than the resolution limit of the optical system. Therefore, itis possible to reproduce the medium identification information by use ofreproduction laser power optimum for a regular optical informationrecording medium. Thus, it is possible to realize a super-resolutionoptical information recording medium capable of identifying the opticalinformation recording medium as a super-resolution optical informationrecording medium by use of reproduction laser power optimum for aregular optical information recording medium.

In order to attain the object, a super-resolution optical informationrecording medium according to the present invention includes: a firstarea in which a content is to be recorded by forming recording marks;and a second area in which medium identification information forspecifying a type of the medium is recorded by use of pre-pits that areformed by concave portions and/or protrusions, a shortest pre-pit lengthin the pre-pits which form the medium identification information islonger than a shortest recording mark length in the recording marks inthe first area.

According to the arrangement, in a recordable/reproduciblesuper-resolution optical information recording medium according to thepresent invention, a shortest pre-pit length in the pre-pits in whichthe medium identification information is recorded is longer than ashortest recording mark length in the recording marks in the first area.Therefore, in a case where the medium identification information isreproduced by a reproduction device having an optical system of whichits resolution limit is not longer than or around a length of theshortest recording mark length in the recording marks in the first area,it is possible to reproduce the medium identification information withreproduction laser power optimum for the regular optical informationrecording medium. Thus, it is possible to realize a super-resolutionoptical information recording medium capable of identifying the opticalinformation recording medium as a super-resolution optical informationrecording medium by use of reproduction laser power optimum for aregular optical information recording medium.

In order to attain the object, a super-resolution optical informationrecording medium according to the present invention includes: a firstarea in which a content is recorded by use of pre-pits that are formedby concave portions and/or protrusions and one or more of which areshorter than a length of a resolution limit of an optical system in areproducing device; and a second area in which medium identificationinformation for specifying a type of the medium is recorded by use ofpre-pits that are formed by concave portions and/or protrusions, thepre-pits which form the medium identification information being notshorter than the resolution limit of the optical system.

According to the arrangement, the medium identification information of asuper-resolution optical information recording medium only forreproduction according to the present invention is recorded by use ofpre-pits that are formed by concave portions and/or protrusions and thatare not shorter than the resolution limit of the optical system.Therefore, it is possible to reproduce the medium identificationinformation by use of reproduction laser power optimum for a regularoptical information recording medium. Thus, it is possible to realize asuper-resolution optical information recording medium capable ofidentifying the optical information recording medium as asuper-resolution optical information recording medium by use of areproduction laser power optimum for a regular optical informationrecording medium.

In order to attain the object, a super-resolution optical informationrecording medium according to the present invention includes: a firstarea in which a content is recorded by use of pre-pits that are formedby concave portions and/or protrusions; and a second area in whichmedium identification information for specifying a type of the medium isrecorded by use of pre-pits that are formed by concave portions and/orprotrusions, a shortest pre-pit length in the pre-pits which form themedium identification information is longer than a shortest pre-pitlength in the pre-pits in the first area.

According to the arrangement, a shortest pre-pit length in the pre-pitsin which the medium identification information is recorded, in asuper-resolution optical information recording medium only forreproduction according to the present invention, is longer than ashortest recording mark length in the recording marks in the first area.Therefore, in a case where the medium identification information isreproduced by a reproduction device having an optical system of whichits resolution limit is not longer than or around a length of theshortest recording mark length in the recording marks in the first area,it is possible to reproduce the medium identification information withreproduction laser power optimum for the regular optical informationrecording medium. Thus, it is possible to realize a super-resolutionoptical information recording medium capable of identifying the opticalinformation recording medium as a super-resolution optical informationrecording medium by use of a reproduction laser power optimum for aregular optical information recording medium.

An optical information recording medium reproducing device according tothe present invention is capable of reproducing (i) the super-resolutionoptical information recording medium, and (ii) a regular opticalinformation recording medium which is an optical information recordingmedium in which recording marks or pre-pits are not shorter than theresolution limit of the optical system, the optical informationrecording medium reproducing device including: reproduction means forreproducing information recorded in a desired position of the opticalinformation recording medium; and control means for controllingoperations of the optical information recording medium reproducingdevice, the control means including: identification informationacquisition means for controlling the reproduction means to reproduceand acquire medium identification information by using reproductionlight power suitable for reproduction of the regular optical informationrecording medium; and medium identification means for identifyingwhether or not the optical information recording medium is asuper-resolution optical information recording medium, based on themedium identification information thus acquired.

By having the above arrangement, the reproducing device is capable ofidentifying whether or not a provided optical information recordingmedium is the super-resolution optical information recording medium, byuse of reproduction light power suitable for the regular opticalinformation recording medium, accurately and with ease. Thus, it ispossible to realize a reproducing device capable of reproducing both thesuper-resolution optical information recording medium and the regularoptical information recording medium. Since the identification iscarried out by use of reproduction light power suitable for the regularoptical information recording medium, electricity consumption of thereproduction device is reduced. Furthermore, no breakage of the regularoptical information recording medium occur due to reproduction lightpower optimum for the super-resolution optical information recordingmedium, since the identification is carried out by use of reproductionlight power suitable for the regular optical information recordingmedium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates one embodiment of the present invention, and is aperspective view illustrating an outer appearance of a super-resolutionmedium.

FIG. 2 is a plan view schematically illustrating an essentialarrangement of a substrate of the super-resolution medium.

FIG. 3 is a cross sectional view schematically illustrating anarrangement of the super-resolution medium.

FIG. 4 is a block diagram schematically illustrating an arrangement ofan optical information recording medium reproducing device capable ofreproducing the super-resolution medium and a regular medium.

FIG. 5 is a block diagram schematically illustrating an arrangement of acontrol section of the optical information recording medium reproducingdevice.

FIG. 6 is a flow chart illustrating a process operation of the opticalinformation recording medium reproducing device.

FIG. 7( a) is an explanatory drawing illustrating a relationship betweena pre-pit and an output signal when a regular medium is reproduced byuse of a reproduction clock suitable for a regular medium.

FIG. 7( b) is an explanatory drawing illustrating relationship between apre-pit and an output signal when a regular medium is reproduced by useof a reproduction clock suitable for a super-resolution medium.

FIG. 8 is a graph illustrating dependency of C/N on reproduction laserpower, for a shortest pre-pit and a longest pre-pit.

FIG. 9 is a graph illustrating dependency of C/N on a pit length, foreach material of a super-resolution reproduction layer.

FIG. 10( a) is an explanatory drawing illustrating a cross sectionalarrangement of a rewritable BD type medium.

FIG. 10( b) is an explanatory drawing illustrating a cross sectionalarrangement of a rewritable DVD type medium.

FIG. 11 is an explanatory drawing illustrating a cross sectionalarrangement of a DVD type medium only for reproduction.

FIG. 12( a) is an explanatory drawing illustrating a cross sectionalarrangement of a medium only for reproduction, having a differentarrangement to the arrangement shown in FIG. 3.

FIG. 12( b) is an explanatory drawing illustrating a cross sectionalarrangement of a medium only for reproduction, having a differentarrangement to the arrangement shown in FIG. 11.

FIG. 13 is an explanation drawing illustrating a cross sectionalarrangement of a BD type medium only for reproduction in a case where aheat radiation layer is provided in the medium only for reproductionhaving a cross sectional arrangement of a BD type as shown in FIG. 12(a).

FIG. 14 is a perspective view illustrating an essential arrangement of asubstrate in a regular medium.

FIG. 15 is a perspective view illustrating an outer appearance of theregular medium.

FIG. 16 is a perspective view illustrating an essential arrangement of asubstrate in a generally conceivable super-resolution medium.

FIG. 17 is a perspective view illustrating an outer appearance of thesuper-resolution medium.

FIG. 18 is a cross sectional view schematically illustrating thesuper-resolution medium.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

One embodiment of the present invention is described below withreference to FIGS. 1 through 3. The present embodiment is described byhaving a super-resolution optical information recording medium only forreproduction of which its cross sectional arrangement is of a BD type(hereafter referred to as a super-resolution medium 1) discussed as anexample. In the following description, a reproducing device 10 denotesan optical information recording medium reproducing device 10 laterdescribed, capable of reproducing both the super-resolution medium 1according to the present embodiment and a regular optical informationrecording medium.

FIG. 1 illustrates an outer appearance of the super-resolution medium 1according to the present embodiment.

FIG. 2 illustrates an enlarged view of section a in the super-resolutionmedium 1. A pre-pit having a length R2T shown in FIG. 2 is a shortestpre-pit in (i) a test read area 3A later described and (ii) a mediuminformation area (second area) 3 excluding area position information. Apre-pit having a length R8T is a longest pre-pit in the mediuminformation area 3. Similarly, a pre-pit having a length D2T is ashortest pre-pit in a data area (first area) 2, and a pre-pit having alength D8T is a longest pre-pit in the medium information area 3, asshown in FIG. 2.

As shown in FIG. 1, the super-resolution medium 1 has the data area 2and the medium information area 3 in advance. A content such as videoimage and software is recorded in the data area 2, and informationconcerning the super-resolution medium 1 is recorded in the mediuminformation area 3.

FIG. 3 illustrates a cross sectional view of the super-resolution medium1. The super-resolution medium 1 includes a substrate 4, and (i) areflection layer 5 and (ii) a super-resolution reproduction layer 6which causes a super-resolution phenomenon to occur are layered on thesubstrate 4 in this order by sputtering. Furthermore, a transparentcover layer 7 is provided on the super-resolution reproduction layer 6.The substrate 4 and the cover layer 7 are made of polycarbonate. Thereflection layer 5 is made of aluminum. Furthermore, thesuper-resolution reproduction layer 6 is made of zinc oxide.

The data area 2 is provided between the medium information areas 3, asillustrated in FIG. 1. The content is recorded by providing pre-pitsthat are formed by concave portions and/or protrusions on the substratewhen the substrate is formed. The pre-pits are pre-pits in a length in arange of lengths D2T to D8T as illustrated in FIG. 2, and their shortestlength is shorter than a resolution limit of an optical system in thereproducing device 10. More specifically, the content is recorded by useof the pre-pits including a pre-pit shorter in length than theresolution limit of the optical system in the reproducing device 10(super-resolution recording form). Thus, recording with a density higherthan the regular medium is possible. The data area 2 is (1, 7) RLLmodulated, however it is not limited to this, and may be of any formprovided that recording is carried out by use of a random pattern.

Information is recorded by use of the pre-pits or recording marks withdifferent lengths such as the (1, 7) RLL modulation, since recordingdensity increases as compared to recording information by use ofpre-pits or recording marks of a same length. Other modulation types arealso possible (for example, 8/16 modulation, (2, 7) RLL modulation), andare referred to as recording by use of a random pattern.

Furthermore, as illustrated in FIG. 3, the pre-pit is reproducible byhaving the super-resolution reproduction layer 6. More specifically, alaser spot is generated by irradiation of reproduction laser light tothe pre-pit. Due to a temperature distribution generated by a lightintensity distribution in the laser spot on the super-resolutionreproduction layer 6, a distribution of a transmittance is generated. Asa result, the laser spot is shrunk in a pseudo manner, thereby thepre-pit is made reproducible. This allows more information to be usableas compared to a regular medium. The super-resolution reproduction layer6 is not particularly limited, provided that the pre-pit isreproducible, and may be, for example, the mask layer as described inPatent Document 2, or the functional layer as described in PatentDocument 3.

The medium information area 3 is provided at an innermostcircumferential section and an outermost circumferential section of thesuper-resolution medium 1 in advance, as illustrated in FIG. 1.Information concerning the super-resolution medium 1 is recorded by useof pre-pits that are formed by concave portions and/or protrusions(regular recording form). The pre-pits are pre-pits having a length in arange of lengths R2T to R8T. A shortest length of the pre-pits is longerthan a resolution limit of an optical system in the reproducing device10. In other words, the shortest pre-pit length in a pre-pit group ofthe medium information area 3 is longer than the shortest pre-pit lengthin the pre-pit group of the data area 2. The medium information area 3is provided at the inner circumference and the outer circumference ofthe super-resolution medium 1, however it is not limited to this, andmay be provided on just one of the inner circumference and the outercircumference.

Information concerning the super-resolution medium 1 encompass: mediumidentification information indicating that the medium includes a dataarea 2; reproduction speed information to be used when the reproducingdevice 10 carries out reproduction; medium unique number used for copyprotection; and area position information for specifying a position inthe data area 2.

The medium identification information is sufficient provided that a typeof medium is specified therefrom, and is not particularly limited aslong as at least the information indicates whether the data area 2 is ina super-resolution recording form or a regular recording form.

The reproduction speed information encompass (i) so-called reproductioninformation required in order to obtain an analog waveform which can bedigitized, when an appropriate reproduction laser is irradiated, and(ii) digital processing information required in order to digitize ananalog waveform reproduced so as to reproduce contents and the like.

The reproduction information includes, for example, reproduction speedrange information. The reproduction speed range information isinformation which specifies reproduction speed in order to stably obtainan analog waveform based on super-resolution reproduction. This isbecause in a case where the super-resolution reproduction is possible byuse of heat, if the reproduction speed is too fast, super-resolutionreproduction is impossible because of insufficient heat, whereas if thespeed is too slow, the heat energy to be generated is too great, therebycausing damage to the medium.

The digital processing information includes, for example, reproductionclock switching information and reproduction speed switchinginformation. The reproduction clock switching information and thereproduction speed switching information are information required inorder to digitize an obtained analog waveform, when random patternshaving different recording densities is reproduced. More details arelater described.

A test read area 3A is provided in the medium information area 3, asillustrated in FIG. 2. The test read area 3A adjusts reproduction laserpower to be used in order for the reproducing device 10 to reproduce thecontents recorded in the data area 2. In the test read area 3A, pre-pitsthat are formed by concave portions and/or protrusions are formed in asame recording density and modulation type as the pre-pits in the dataarea 2. The test read area 3A may have pre-pits having (i) a lengthlonger than the shortest pre-pit length in the pre-pits in the data area2 and (ii) a length shorter than the longest pre-pit length in thepre-pits in the data area 2, i.e., a pre-pit longer than D2T but shorterthan D8T, as illustrated in FIG. 2. For example, pre-pits having alength as illustrated in FIG. 2 are formed. The pre-pit illustrated witha broken line in the test read area 3A for comparison is the shortestpre-pit in the data area 2.

As described above, the medium information area 3 of thesuper-resolution medium 1 according to the present embodiment haspre-pits formed that are not shorter than a resolution limit of anoptical system in the reproducing device 10. Thus, it is possible forthe reproducing device 10 to reproduce various information such as themedium identification information, the reproduction speed informationand the medium unique number.

The test read area 3A is preferably provided at a position closer to thedata area 2 in the medium information area 3 than the position of thepre-pits in which the medium identification information is recorded.This arrangement enables efficient information recording and/orinformation reproduction. The following description explains the reasonsof this, with reference to examples.

For example, reproduction is carried out as follows in a medium in which(i) a medium information area is provided on an inner circumferentialside than the data area on the medium, and (ii) a test read area isprovided on an inner circumferential side of pre-pits in which themedium identification information is recorded. Namely, reproduction iscarried out as follows in a medium in which the test read area isprovided at a position far from the data area than the position of thepre-pits in which the medium identification information is recorded.

First, the reproducing device reproduces the medium identificationinformation in order to identify a type of medium. Then, an optical headis moved to the test read area included on the inner circumferentialside of the medium, and a test read is carried out. This determinesreproduction laser power and the like. Thereafter, the optical head ismoved to the data area on an outer circumferential side of pre-pits inwhich the medium identification information is recorded, by which thecontent in the data area is reproduced. As such, the reproducing devicerequires the optical head to reciprocate in order to start reproduction,if the test read area is provided in the medium information area at aposition far from the data area than the pre-pits are in which themedium identification information is recorded. As a result, problemsoccur that (i) reproduction start-up time is increased, and (ii)breakage rate of the reproducing device caused by complex movement ofthe optical head is increased.

In comparison, the optical head just requires to move in one directionif the test read area 3A is provided in the medium information area 3 ata position closer to the data area 2 than the pre-pits are in which themedium identification information is recorded, as like thesuper-resolution medium 1. Thereby, the optical head does not need tomake any complex movements. Therefore, it is possible to shorten thereproduction start-up time, and reduce the breakage rate of thereproducing device.

The above description explains a case where the test read area 3A isprovided closer to the data area 2 than the pre-pits are in which themedium identification information is recorded, in a radius direction.However, it is not limited to this, and the same applies for a casewhere the test read area 3A is provided closer to the data area 2 in adirection in which the pre-pits and grooves are arranged (same directionas a direction in which reproduction is carried out). The same alsoapplies for the following description which describes pre-pits providedclose to or far from the data area 2.

The pre-pit in which the reproduction speed information is recorded ispreferably provided at a position far from the data area 2 than the testread area 3A is. This arrangement allows reproduction of thereproduction speed information by use of reproduction laser poweroptimum for a regular medium. It is also possible to determine, in thetest read area 3A, reproduction laser power for reproducing the contentrecorded in the data area 2, provided that the reproduction speedinformation is obtained. Specifically, it is possible to digitize ananalog waveform obtained in a reproduction speed at which stablesuper-resolution reproduction can be attained, in a state adapted to arecording density of the test read area 3A. Therefore, no mistakes occurin determination of the reproduction laser power.

The reproduction speed denotes a linear velocity in reproduction (arelative velocity of an optical head in a reproduction positionreproduction direction, caused by rotation of a medium by a spindlemotor when the medium is reproduced).

It is possible to appropriately digitize the analog waveform obtained ata reproduction speed at which stable super-resolution reproduction canbe attained, even in reproduction of the contents recorded in the dataarea 2. Therefore, it is possible to stably reproduce the contents.

The pre-pit in which the area position information is recorded ispreferably provided at a position closer to the data area 2 than thetest read area 3A is. This arrangement allows reproduction of the areaposition information by use of reproduction laser power optimum for theregular medium. This arrangement also allows, after determination of thereproduction laser power, reproduction of the area position informationwithout making any changes to the determined reproduction laser power.This simplifies the movement taken by the optical head (movement in onedirection). Thus, an efficient information recording and/or informationreproduction is possible. Furthermore, the medium information area 3 canbe made narrow, and the data area 2 be made wide, thereby increasing aninformation recording capacitance as a result.

The medium unique signal is different for each manufactured medium.Therefore, the medium unique signal cannot not formed by compressionmolding of a highly productive substrate as like the pre-pits, and isusually created by forming a groove section on the substrate with alaser or the like, at the end of creating the medium.

A wavelength of a significant power laser to be used in order to createthe medium unique signal increases in cost if the wavelength is of ashort wavelength, as like one used in optical disc reproduction.Therefore, usually, the wavelength is made longer than the one used inthe optical disc reproduction (the wavelengths are long, therefore asmall groove section obviously cannot be made). In addition, since agroove section is formed by use of the significant power laser, themedium unique signal has damage in the first place. Therefore, there isa high possibility that reproduction by use of a high laser power whichreadily gives damage may cause reproduction deterioration of the mediumunique signal. As such, the reproduction of the medium unique signal ispreferably carried out by use of low laser power.

In view of this, the super-resolution medium 1 provides the pre-pit inwhich the medium unique number is recorded at a position far from thedata area 2 than the test read area 3A is. This allows reproduction ofthe medium unique signal by use of reproduction laser power optimum fora regular medium, that is to say, low laser power. Thereby, it ispossible to securely reproduce the medium unique signal. In addition, nowasteful switching of laser power is carried out. Therefore, efficientinformation recording and/or the information reproduction is/arepossible.

Although the present embodiment is described above by discussing thesuper-resolution medium 1 as an example, which is a medium only forreproduction, the super-resolution optical information recording mediumof the present invention obviously includes a recordable/reproduciblesuper-resolution optical information recording medium. A main differencebetween the recordable/reproducible super-resolution optical informationrecording medium and the super-resolution medium 1 is, that a test writeread area is provided instead of the test read area 3A. In the testwrite read area, information which adjusts (i) a recording laser powerfor a reproducing device 10 to be used to record contents in a data areaand (ii) a reproduction laser power for the reproducing device 10 to beused to reproduce the contents in the data area are recorded having asame recording density and modulation type as the recording mark groupto be formed in the data area.

In the medium information area of the recordable/reproduciblesuper-resolution optical information recording medium, recordingcondition information for recording contents in the data area isrecorded by use of pre-pits that are formed by concave portions and/orprotrusions and that are not shorter than a resolution limit of anoptical system in the reproducing device 10. The pre-pits that areformed by concave portions and/or protrusions thus recorded with therecording condition information are preferably provided at a positionfar from the data area than the test write read area is. Thisarrangement allows determination of reproduction laser power at the testwrite read area based on the recording condition information, and as aresult, a determination mistake of the reproduction laser power does notoccur. The recording condition information includes not only therecording laser power, but also removal laser power for forming arecording mark, a pulse width and a timing of a laser, and the like.

Second Embodiment

The following description explains another embodiment of the presentinvention, with reference to FIGS. 4 through 6. FIG. 4 schematicallyillustrates an arrangement of a reproducing device 10 according to thepresent embodiment. The reproducing device 10 of the present embodimentis capable of reproducing both the super-resolution medium 1 of FirstEmbodiment and a regular medium.

The reproducing device 10 includes a laser control circuit 14A, a signalprocessing circuit 14B, a head amplifier 16, an RF amplifier 17A, asignal processing circuit 17B of an RF signal, a servo processingcircuit 18, a control section 19 (control means), a spindle motor 20, alight pickup 21 (reproduction means), and a light pickup motor 22, asillustrated in FIG. 4. The light pickup 21 includes a polarization beamsplitter 12, a laser light source 13, and a detector 15. An opticalinformation recording medium 11 shown in FIG. 4 may be thesuper-resolution medium 1 or may be a regular medium.

The reproducing device 10 first causes the optical information recordingmedium 11 to rotate by use of the spindle motor 20. The light pickup 21is moved by controlling the light pickup motor 22 with the controlsection 19. Next, power of reproduction laser light to be irradiatedfrom a laser light source 13 caused by the laser control circuit 14A ismade to be a predetermined reproduction laser power (reproduction laserpower for a regular medium). Thereafter, the reproduction laser light isirradiated from the laser light source 13. The reproduction laser lightis irradiated to the optical information recording medium 11 via apolarization beam splitter 12. Then, light reflected from the lightinformation recording medium 11 reaches a detector 15 via thepolarization beam splitter 12.

The detector 15 outputs an electric signal based on the reflected lightthus reached. The electric signal is amplified at the head amplifier 16,thereafter is sent to the servo processing circuit 18. Various servocontrols are carried out at the servo processing circuit 18. Inaddition, the electric signal is also sent to the control section 19.

FIG. 5 illustrates an arrangement of the control section 19. The controlsection 19 includes an access position control section 23, a signalprocessing section 24 (identification information acquisition means), amedium identification section 25 (medium identification means), a powercontrol section 26 (power control means), and a reproduction clockcontrol section 27 (reproduction clock control means), as illustrated inFIG. 5.

The access position control section 23 controls the light pickup motor22 so that the light pickup 21 accesses a desired position of theoptical information recording medium 11. In a case a track pitch of adata area 2 and a track pitch of a medium information area 3 aredifferent in the super-resolution medium 1, it is desirable for theaccess position control section 23 to control an access position basedon an identification result of the optical information recording medium11 identified by the medium identification section 25.

The signal processing section 24 processes a medium identificationsignal received from the head amplifier 16, and supplies the mediumidentification signal thus processed to the medium identificationsection 25. The medium identification section 25 carries outidentification of the optical information recording medium 11, based onthe medium identification signal supplied from the signal processingsection 24.

The power control section 26, based on an identification result of theoptical information recording medium 11 determined by the mediumidentification section 25, either (i) leaves the reproduction laserpower of the laser light source 13 as it is (that is to say, asreproduction laser power suitable for a regular medium), or (ii)switches the reproduction laser power to reproduction laser powersuitable for the super-resolution medium 1 by controlling the lasercontrol circuit 14A. The reproduction clock control section 27, based onthe identification result of the optical information recording medium 11determined by the medium identification section 25, either (i) leavesthe reproduction clock to be used at the signal processing circuit 17Bas it is (that is to say, as the reproduction clock suitable for aregular medium), or (ii) switches the reproduction clock to thereproduction clock suitable for a super-resolution medium.

The following description explains a processing operation of thereproducing device 10 with reference to FIG. 6. FIG. 6 illustrates aflow of processing operations in the reproducing device 10.

Once the optical information recording medium 11 is provided in thereproducing device 10, the light pickup motor 22 is controlled by theaccess position control section 23 in the control section 19, and inresponse, a reproduction laser light from the laser light source 13 isirradiated to a medium information area, which is an initial accessposition of the optical information recording medium 11, based onreproduction laser power for a regular medium determined in advance forinitial reproduction (S1). Thereafter, medium identification informationwhich indicates whether the light information recording medium 11 is asuper-resolution medium or a regular medium, that is to say, a mediumidentification signal of a medium identification information indicatingwhether or not a data area of the optical information recording medium11 is of a super-resolution form, is reproduced (S2). The mediumidentification signal is processed by the signal processing section 24in the control section 19, via the detector 15 and the head amplifier16, by which identification of the light information recording medium 11is carried out at the medium identification section 25 (S3).

When the identification result determined by the medium identificationsection 25 indicates a regular medium (NO in S3), a data area of theregular medium is accessed without any modification to the reproductionlaser power and the reproduction clock (S6). Thereafter, content in thedata area is reproduced via the detector 15, the head amplifier 16, theRF amplifier 17A, and the signal processing circuit 17B (S7).

On the other hand, if the identification result determined by the mediumidentification section 25 indicates the super-resolution medium 1 (YESin S3), the reproducing device 10 reads out a pre-pit in the test readarea 3A provided in the medium information area 3 of thesuper-resolution medium 1. A reproduction signal which has read thepre-pit is supplied to the power control section 26 in the controlsection 19, via the detector 15, the head amplifier 16, and the signalprocessing section 24. The power control section 26 controls the lasercontrol circuit 14A so as to cause the reproduction laser power of thelaser light source 13 to increase based on the reproduction signal sothat the reproduction laser power is adjusted to be optimum for thesuper-resolution medium 1 (S4).

Next, the reproduction device 10 reproduces reproduction clock switchinginformation, recorded in the medium information area 3 of thesuper-resolution medium 1. The reproduction clock switching signal issupplied to the reproduction clock control section 27 in the controlsection 19, via the detector 15, the head amplifier 16, and the signalprocessing section 24. The reproduction clock control section 27, basedon the reproduction clock switching signal, changes the reproductionclock to a reproduction clock for a super-resolution medium specified inadvance (S5). Thereafter, the data area 2 is accessed in reproductionlaser power for the super-resolution medium 1 (S6). A content recordedin the data area 2 is then reproduced, via the detector 15, the headamplifier 16, the RF amplifier 17, and the signal processing circuit 17B(S7).

As described above, since the reproducing device 10 includes thesuper-resolution medium 1 arranged as the aforementioned, it is possiblefor the reproducing device to carry out identification of whether or notthe provided optical information recording medium is thesuper-resolution medium 1, easily and accurately, by use of lowreproduction laser power for a regular medium. The reproducing device 10is also capable of switching reproduction laser power and a reproductionclock suitable for the provided optical information recording medium,based on the identification result.

Thus, the reproducing device 10 can reproduce both the super-resolutionmedium 1 and the regular medium. Since the identification can be carriedout by use of low reproduction laser power for a regular medium,electricity consumption of the reproducing device 10 is suppressed, andfurthermore, breakage of the regular medium is prevented, caused by thereproduction laser power for the super-resolution medium 1.

As described above, in the present embodiment, the reproduction clockswitching information is recorded in the super-resolution medium 1, andthe reproducing device 10 switches the reproduction clock based on thereproduction clock switching information in order to reproducesuper-resolution medium 1. However, the arrangement may be one in whichthe reproduction clock is switched based on an identification result ofthe optical information recording medium. In such a case, recording ofthe reproduction clock switching signal in the super-resolution medium 1is not necessary.

The following description explains a reason for switching a reproductionclock between the super-resolution medium 1 and the regular medium, bydiscussing an example in which a regular medium only for reproduction isreproduced by use of (i) a reproduction clock for a regular medium and(ii) a reproduction clock for a super-resolution medium, with referenceto FIGS. 7( a) and 7(b). The regular medium is (1, 7) RLL modulated.Namely, pre-pits are provided on a substrate which pre-pits have lengthsin a range of a length of a shortest pre-pit 2T to a length of a longestpre-pit 8T, where a length T is a standard channel pit length.

The optical information recording medium reproduces a signal, by (i)irradiating reproduction laser to a pre-pit provided on a substrate, and(ii) binarizing an output signal obtained due to light of thereproduction laser thus reflected, based on whether or not the outputsignal is greater than a slice level set in the reproducing device.

FIG. 7( a) illustrates a state in which (i) the regular medium isreproduced by use of a reproduction clock for the regular medium, and(ii) a signal thus obtained due to the reproduction of the regularmedium is binarized. An output signal corresponds to a respectivepre-pit illustrated on a lower side of the drawing. FIG. 7( b)illustrates a state in which (i) the regular medium is reproduced by useof a reproduction clock for the super-resolution medium 1, and (ii) asignal thus obtained due to the reproduction of the regular medium isbinarized. An output signal corresponds to a respective pre-pitillustrated on a lower side of the drawing.

The following description explains the case where the regular medium isreproduced by use of the reproduction clock for the regular medium. Asillustrated in FIG. 7( a), a 2T pre-pit, a space, and a 4T pre-pit arereproduced. The output signal is binarized at the point the outputsignal corresponds to the reproduction clock of the regular medium, asillustrated in FIG. 7( a). As a result, the values become “1, 1, 0, 0,1, 1, 1, 1”. The signal of “1, 1” is processed as the 2T pre-pit, andthe signal of “1, 1, 1, 1” is processed as the 4T pre-pit. A signallevel V1 at the time of binarizing is sufficiently greater than a slicelevel, as illustrated in FIG. 7( a). Therefore, even if a reasonablechange occurs due to individual specificity of the regular medium andthe reproducing device, stable reproduction is carried out.

The following description explains a case where the regular medium isreproduced by use of the reproduction clock for the super-regular medium1. Assume that the super-resolution medium 1 has a linear density twiceas more as the regular medium. Therefore, a reproduction clock width forthe super-resolution medium 1 is half the width of a reproduction clockwidth for the regular medium.

When the regular medium is reproduced by use of the reproduction clockfor the super-resolution 1, a signal thus binarized becomes “1, 1, 1, 1,0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1”, as illustrated in FIG. 7( b). Assimilar to the reproduction of the regular medium, the signal of “1, 1,1, 1” is processed as a 2T pre-pit, and the signal of “1, 1, 1, 1, 1, 1,1, 1” is processed as a 4T pre-pit.

Thus, it is possible to reproduce the regular medium by use of thereproduction clock for the super-resolution medium 1. However, a signallevel V2 is insufficiently increased in response to the slice level atthe timing in which the value is binarized, as illustrated in FIG. 7(b). This causes a higher possibility of reproduction malfunctionoccurrence due to changes caused by individual difference of the regularmedium and the reproducing device. That is to say, if the reproductionis not carried out with a reproduction clock suitable for the opticalinformation recording medium, the reliability of the reproductiondecreases.

For example, it is also possible to show in a pseudo manner that theregular medium is reproduced by use of a reproduction clock for theregular medium, by (i) reproducing the regular medium by use of areproduction clock for a super-regular medium 1, (ii) sliding a timingof binarizing an output signal, and (iii) the output signal thusbinarized is read in by alternately skipping one value. However, suchsignal processing causes a problem that the process becomes extremelycomplex. Therefore, in order to reproduce the regular medium and thesuper-resolution medium 1 in an optimistic state for each medium, it isrequired to modify the reproduction clock for each case. Therefore, thereproducing device 10 switches the reproduction clock between thesuper-resolution medium 1 and the regular medium.

The reproduction clock switching information is recorded by use of apre-pit having a length longer than the resolution limit of the opticalsystem in the reproducing device 10. Therefore, reproduction by use ofthe reproduction laser power and the reproduction clock for the regularmedium is possible. As a result, wasteful switching of the reproductionlaser power and the reproduction clock is unnecessary.

As described above, the reproducing device 10 switches the reproductionclock between the regular medium and the super-resolution medium 1.However, in such case, circuit load increases, for example a number ofstandard oscillators provided is increased to two, or the like. In viewof this, instead of switching the reproduction clock, a reproductionspeed may be varied.

For example, with a super-resolution medium 1 which has twice a lineardensity of a regular medium, a transmission speed of a signal to bereproduced is also slowed down to half the speed when a reproductionspeed is varied and slows down to half the speed. Therefore, problemssuch as the decrease in reproduction reliability is prevented, even ifthe reproduction clock is not switched. Therefore, the reproducingdevice 10 may be arranged so that the reproduction speed is variedinstead of switching the reproduction clock. In such case, thereproduction speed may be varied based on the reproduction speedswitching information recorded in the medium information area 3 of thesuper-resolution medium 1. The reproducing speed may also be variedbased on the identification result of the optical information recordingmedium. In this case, recording of the reproducing speed switchinginformation in the super-resolution medium 1 is not necessary.

With the arrangement in which the reproduction speed is varied, althoughthe circuit load is reduced as compared to the arrangement in which thereproducing clock is switched, the transmission speed of thesuper-resolution medium 1 becomes the same as the transmission speed ofthe regular medium. On the other hand, with the arrangement in which thereproduction clock is switched, the transmission speed of theinformation of the super-resolution medium 1 can be made faster.

The reproducing device 10 determines an optimum reproduction laser powerby increasing reproduction laser power to be irradiated to the test readarea 3A of the super-resolution medium 1, until a reproduction error isminimized, as similar to a method for determining a recording laserpower in a typical recording and reproducing device.

However, it is also possible to determine the optimum reproduction laserpower by: (i) forming a test read area 3A in the super-resolution medium1 by use of pre-pits that are longer than a shortest pre-pit in thepre-pits of the data area 2 but shorter than a longest pre-pit in thepre-pits of the data area 2, and (ii) increasing the reproduction laserpower until an amplitude of a reproduction signal of the pre-pits in thetest read area 3A is maximized, as described in First Embodiment. Thefollowing description explains this with reference to FIG. 8.

Generally, information is recorded in a data area of a super-resolutionmedium by use of combinations of pre-pits and the like of variouslengths. Therefore, when the pre-pits of various lengths are reproducedin a same reproduction laser power, a C/N (carrier to noise ratio) withrespect to the pre-pits of each length differs, therefore a minimum C/Nvalue is provided. The minimum value changes according to thereproduction laser power, therefore the reproduction laser power whichcauses the pre-pits in various lengths to have the maximum C/N minimumvalues can be considered as the optimum reproduction laser power.

FIG. 8 illustrates the C/N with respect to pre-pits when reproductionlaser power to be irradiated to a shortest pre-pit and a longest pre-pitin the super-resolution medium 1 is changed in a range of 1 mW to 5 mW.The shortest pre-pit has a length of 0.14 μm, and the longest pre-pithas a length of 0.40 μm. The graph in FIG. 8 illustrates the C/N in thevertical axis, and the reproduction laser power in the horizontal axis.

As illustrated in FIG. 8, with the shortest pre-pit, the C/Nmonotonously increases as the reproduction laser power is increased. Onthe other hand, with the longest pre-pit, the C/N increases until thereproduction laser power reaches approximately 2.5 mW, however the C/Nstarts to decrease when the reproduction laser power exceedsapproximately 3.0 mW. With reference to FIG. 8, it is assumable that agraph of the C/N with respect to pre-pits of various lengths ispositioned between the graph of the C/N with respect to the shortestpre-pit and the graph of the C/N with respect to the longest pre-pit.

It is considered from the above that a reproduction laser power in thevicinity of a point where (i) the graph of the C/N with respect to theshortest pre-pit and (ii) the graph of the C/N with respect to thelongest pre-pit intersect with each other is the optimum laser power inwhich the minimum value of the C/N with respect to the pre-pit ofvarious lengths is maximized. Furthermore, it can be expected that apre-pit exists which has a length in which (i) the C/N with respect tothe pre-pit increases until the vicinity of the point thus intersectingis reached and (ii) the C/N with respect to the pre-pit starts todecrease once the vicinity of the intersection point is exceeded.

In the present embodiment, the pre-pits as like the aforementioned areformed as the test read area 3A, in order to adjust the reproductionlaser power. Thus, it is possible for the reproducing device 10 todetermine an optimum reproduction laser power in reproduction of thesuper-resolution medium 1, by increasing the reproduction laser poweruntil an amplitude of the reproduction signal of the pre-pit ismaximized. Of which pre-pit of which length the reproduction laser powercorresponds to is dependent on a thin film layer including asuper-resolution reproduction film 4 and a reflection layer 5.

As described above, an amplitude of a reproduction signal is used inorder to determine an optimum reproduction laser power, therefore it isnot necessary to carry out a determination process for reproductionerrors. As a result, an optimum reproduction laser power is quicklydetermined. In addition, the test read area 3A is provided in the mediuminformation area 3, therefore it is possible to quickly adjust thereproduction laser power of the data area 2.

The test read area 3A is not limited to the above pre-pits. For example,the shortest pre-pit and the longest pre-pit may be formed as the testread area 3A. In such case, the reproducing device 10 can determine theoptimum reproduction laser power in reproduction of the super-resolutionmedium 1, by increasing the reproduction laser power until theamplitudes of the reproduction signals for each of the shortest andlongest pre-pit match each other.

The reproducing device 10 may also determine the optimum reproductionlaser power in the following method: (i) a C/N slightly lower than thepoint thus intersecting is set as a C/N threshold value, and a signalamplitude corresponding to the C/N threshold value is set as anamplitude threshold value, and (ii) the reproduction laser power isincreased by the reproducing device until the amplitude is not less thanthe amplitude threshold value. A C/N obtained from a pre-pit made from asame master disc is substantially the same between the opticalinformation recording mediums, provided that the thin film layer whichincludes the super-resolution reproduction layer 4 and the reflectionlayer 5 is the same. Therefore, it is possible to use the amplitudethreshold value as it is for a same master disc.

The reproduction laser power determination method usable in the presentinvention is not limited to the above method. For example, thereproduction laser power may be (i) recorded in the medium informationarea 3 in advance, or (ii) substantially determined or determined basedon the medium identification information itself. In the former casewhere the reproduction laser power is recorded in the medium informationarea 3 in advance, a combined use of (i) the medium identificationinformation, and (ii) the method determining an optimum reproductionlaser power by increasing the reproduction laser power to be irradiatedto the test read area 3A until a reproduction error is minimized,enables accurate determination of the reproduction laser power. As aresult, determination of the reproduction laser power is quickened,thereby a start-up time of the reproducing device quickens. On the otherhand, in the latter case where the reproduction laser power issubstantially determined or determined based on the mediumidentification information itself, as long as the clock switchinginformation or linear velocity modification information is concurrentlyincluded in a medium identification number, other information requiredfor reproduction may be recorded as similar to the data area 2. In suchcase, capacity of the data area 2 is secured even more, thereby allowingan increase in recording capacitance of the medium.

The following description explains a track pitch of the data area 2 (TpDshown in FIG. 2) and a track pitch of the medium information area 3 (TpRshown in FIG. 2). The track pitch TpD of the data area 2 is desirablythe same as or narrower than the track pitch TpR of the mediuminformation area 3. FIG. 2 illustrates a case where the track pitch TpDof the data area 2 is narrower than the track pitch TpR of the mediuminformation area 3.

If the track pitch TpD of the data area 2 and the track pitch TpR of themedium information area 3 are the same, although it is not possible toincrease the number of tracks in the data area 2, it is possible toincrease density of recorded information without providing a mechanismto change the track pitch in the reproducing device 10.

On the other hand, if the track pitch TpD of the data area 2 is narrowerthan the track pitch TpR of the medium information area 3, it ispossible to increase the number of tracks in the data area 2, therebyallowing further increase in density of recorded information. However,it is necessary to provide in the reproducing device a mechanism forchanging the track pitch. A laser spot is shrunken in a pseudo manner byuse of the super-resolution reproduction layer 6, even in this case.Therefore, no deterioration in cross talk characteristic norunstableness in tracking occur.

The following description explains the super-resolution reproductionlayer 6 illustrated in FIG. 3. The super-resolution reproduction layer 6desirably is a metal oxide film, particularly a metal oxide film madefrom metal oxides such as zinc oxide, cerium oxide, or titanium oxide,or is an inorganic film whose main component is the zinc oxide, ceriumoxide, or titanium oxide. Such super-resolution reproduction layer 6attains excellent super-resolution characteristics and sufficientreproduction durability. The following description explains a reason whythe effect is attained, with reference to FIG. 9.

FIG. 9 illustrates a spatial resolution of the super-resolution medium1, when a metal oxide film is used as the super-resolution reproductionlayer 6. The metal oxide film is formed by applying approximately 120 nmof zinc oxide, cerium oxide or titanium oxide by sputtering. Thearrangement of the super-resolution medium 1 which includes the metaloxide film as the super-resolution reproduction layer 6 is as similar tothat of FIG. 3, arranged such that a reflection layer 5 and asuper-resolution reproduction layer 6 (the metal oxide film), and also acover layer 7 are provided on a substrate 4. The substrate 4 and thecover layer 7 are made of polycarbonate, and the reflection layer 5 ismade of aluminum nickel film having a thickness of 50 nm. Reproductionof the super-resolution medium 1 is carried out by an evaluation machineincluding an optical system which has a reproduction laser wavelength of408 nm and a numerical aperture NA of 0.65. A reproduction laser powerPr is set as 3.5 mW. A reproduction laser power for a regular medium isusually around 1.0 mW.

As clearly shown in FIG. 9, the C/N is detected for all three types ofmetal oxide films, even for the pre-pits that are shorter than theresolution limit of the optical system in the evaluation machine. Thatis to say, it is obvious that the three types of metal oxide films areusable as the super-resolution reproduction layer. Super-resolutioncharacteristics of the three types of metal oxide films improve in orderof titanium oxide, cerium oxide and zinc oxide. Particularly, the zincoxide and the cerium oxide show better super-resolution characteristicsthan the titanium oxide.

Furthermore, the metal oxide film excels in durability againsttemperature change due to heat, as compared to organic materials.Therefore, the metal oxide film excels in reproduction durability ascompared to a super-resolution reproduction layer made of organicmaterial disclosed in Patent Document 2. A result of a reproductiondurability test carried out for the super-resolution medium 1 which useszinc oxide as the super-resolution reproduction layer 6 showed nodeterioration, as assumed. Specifically, it is possible to realize asuper-resolution medium 1 which excels in super-re solutioncharacteristic and reproduction durability as compared to a conventionalsuper-resolution medium, by use of the zinc oxide film as thesuper-resolution reproduction layer 6.

The Embodiment above is explained by discussing the super-resolutionmedium 1 only for reproduction whose cross sectional structure is of theBD type as an example, however the present invention is not limited tothis, and is applicable to various optical information recording mediumsas illustrated in FIGS. 10 through 12.

FIGS. 10( a) and 10(b) illustrate a rewritable medium; FIG. 10( a)illustrates a BD type cross sectional structure, and FIG. 10( b)illustrates a DVD type cross sectional structure. FIG. 11 illustrates amedium only for reproduction having a DVD type cross sectionalstructure. FIGS. 12( a) and 12(b) illustrate a medium only forreproduction; FIG. 12( a) illustrates a cross sectional structure inwhich the reflection layer 5 as illustrated in FIG. 3 is a lightabsorbing layer which absorbs reproduction laser and converts thereproduction laser to heat, and FIG. 10( b) illustrates a crosssectional structure in which the reflection layer illustrated in FIG. 11is a light absorbing layer.

The rewritable medium whose cross sectional structure is of a BD type,as illustrated in FIG. 10( a), is arranged so that a reflection layer31, a recording layer 32, and a super-resolution reproduction layer 33are layered on a substrate 30 in this order, and is further providedwith a cover layer 34. The rewritable medium whose cross sectionalstructure is of a DVD type, as illustrated in FIG. 10( b), is arrangedso that a super-resolution reproduction layer 36, a recording layer 37,and a reflection layer 38 are layered on a transparent substrate 35 inthis order, and is further provided with a cover layer 39. The mediumonly for reproduction whose cross sectional structure is of a DVD type,as illustrated in FIG. 11, is arranged so that a super-resolutionreproduction layer 41 and a reflection layer 42 are layered on atransparent substrate 40 in this order, and is further provided with acover layer 43.

The medium only for reproduction whose cross sectional structure is of aBD type, as illustrated in FIG. 12( a), is arranged so that a lightabsorbing layer 45 and a super-resolution reproduction layer 46 arelayered on a substrate 44 in this order, and is further provided with acover layer 47. The medium only for reproduction whose cross sectionalstructure is of a DVD type, as illustrated in FIG. 12( b), is arrangedso that a super-resolution reproduction layer 49 and a light absorbinglayer 50 are layered on a transparent substrate 48 in this order, and isfurther provided with a cover layer 51.

Generally, when reproduction of (i) a super-resolution medium having asuper-resolution reproduction layer made of a metal oxide film or (ii) asuper-resolution medium using a super-resolution reproduction layerdescribed in Patent Document 2 is to be carried out, a temperature in alaser spot generated due to the reproduction laser is required to beincreased to at least a predetermined temperature. As illustrated inFIGS. 12( a) and 12(b), the temperature in the laser spot is easilyincreased in an arrangement which includes the light absorbing layer 45or 50, thereby sensitivity is improved.

As a result, the reproduction laser power can be set low, therebyallowing reduction of electricity consumption of the reproducing device.A super-resolution medium which uses the super-resolution reproductionlayer made of zinc oxide particularly showed improvement in sensitivity.In addition, reproduction durability further improves, because of adecrease in requirement of the super-resolution reproduction layer toabsorb the reproduction laser and generate heat by the super-resolutionreproduction layer itself. Specific materials used for the lightabsorbing layers 45 and 50 encompass Si, Ge, or an alloy whose maincomponent is Si and/or Ge, however the material used for the lightabsorbing layer is not limited to this.

A heat releasing layer which releases heat generated due to irradiationof the reproduction laser may be provided in the super-resolution medium1 and the various optical information recording mediums illustrated inFIGS. 10 through 12. FIG. 13 illustrates a cross sectional structurewhere a heat releasing layer 52 is provided in a medium only forreproduction as illustrated in FIG. 12( a), whose cross sectionalstructure is of a BD type. Excess accumulation of heat generated due toirradiation of the reproduction laser is prevented by providing the heatreleasing layer 52. Therefore, reproduction durability is improved,thereby signal reproduction of a further high reliability is carriedout. Signal reproduction having a further high reproduction durabilityand reliability is possible, by forming the heat releasing layer 52 byuse of a highly heat-conductive metal film.

The metal film of the heat releasing layer has a high reflection rate.Thus, the heat releasing layer also functions as a reflection layer.Therefore, a reflection layer is not necessarily provided when the heatreleasing layer is provided.

As long as the film arrangement shows super-resolution characteristics,the film arrangement of the super-resolution medium claimed in thepresent application is not limited to the above. For example, the filmarrangement may be one described in Patent Documents, or may be filmarrangements described in International Patent No. WO2002/058060 andso-called Super Lens, described in Appi. Phys. Lett, 73, 2078-2080.

Finally, blocks of the control section 19 of the optical informationrecording medium reproducing device 10 may be realized by way ofhardware or software as executed by a CPU as follows.

The optical information recording medium reproducing device 10 includesa CPU (central processing unit) and memory devices (memory media). TheCPU (central processing unit) executes instructions in control programsrealizing the functions. The memory devices include a ROM (read onlymemory) which contains programs, a RAM (random access memory) to whichthe programs are loaded, and a memory containing the programs andvarious data. The objective of the present invention can also beachieved by mounting to the optical information recording mediumreproducing device 10 a computer-readable storage medium containingcontrol program code (executable program, intermediate code program, orsource program) of the control program of the control section 19 for theoptical information recording medium reproducing device 10, which issoftware realizing the aforementioned functions, in order for thecomputer (or CPU, MPU) to retrieve and execute the program codecontained in the storage medium.

The recording medium may be, for example, a tape, such as a magnetictape or a cassette tape; a magnetic disk, such as a floppy (RegisteredTrademark) disk or a hard disk, or an optical disk, such asCD-ROM/MO/MD/DVD/CD-R; a card, such as an IC card (memory card) or anoptical card; or a semiconductor memory, such as a maskROM/EPROM/EEPROM/flash ROM.

The optical information recording medium reproducing device 10 may bearranged to be connectable to a communications network so that theprogram code may be delivered over the communications network. Thecommunications network is not limited in any particular manner, and maybe, for example, the Internet, an intranet, extranet, LAN, ISDN, VAN,CATV communications network, virtual dedicated network (virtual privatenetwork), telephone line network, mobile communications network, orsatellite communications network. The transfer medium which makes up thecommunications network is not limited in any particular manner, and maybe, for example, wired line, such as IEEE 1394, USB, electric powerline, cable TV line, telephone line, or ADSL line; or wireless, such asinfrared radiation (IrDA, remote control), Bluetooth, 802.11 wireless,HDR, mobile telephone network, satellite line, or terrestrial digitalnetwork. The present invention encompasses a carrier wave or data signaltransmission in which the program code is embodied electronically.

As the optical information recording medium, various optical discs maybe suggested, such as optical scanning discs such as CD-ROM (CompactDisk Read Only Memory), CD-R (Compact Disk Recordable), CD-RW (CompactDisk Rewritable), DVD-ROM (Digital Versatile Disk Read Only Memory),DVD-RW (Digital Versatile Disk Rewritable), BD (Blu-ray Disc), and BD(Blu-ray Disc)-ROM, magneto-optical discs, phase-change discs, and thelike. The present invention is not limited to a particular recordingtype or a particular size of the optical information recording medium.

Furthermore, the optical information recording medium reproducing deviceencompasses a device only for reproduction or only for recording, aswell as a device capable of carrying out both reproduction andrecording. The optical information recording medium reproducing devicemay be portable type or non-portable type.

The invention being thus described, it will be obvious that the same waymay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

A super-resolution optical information recording medium according to anembodiment of the present invention is preferably arranged such that thesecond area has a test write read area in which (i) information foradjusting laser light power for recording the content to the first areaand (ii) information for adjusting laser light power for reproducing thecontent recorded in the first area are recordable; and recording marksin the test write read area are formed having a same recording densityand modulation type as the recording marks to be formed in the firstarea.

In order to determine laser light power for recording contents(hereafter referred to as recording laser power), a conventionalrecording and reproducing device gradually raises recording laser poweruntil a reproduction error specified by a standard is minimized. At apoint the reproduction error is increased, the conventional recordingand reproducing device determines that the recording laser powerimmediately before the increase is an optimum recording laser power.

Reproduction of a regular medium does not require determination of anoptimum reproduction laser power for the reproducing device. This isbecause (i) the laser light power for reproducing contents (hereafterreferred to as reproduction laser power) is standardized in accordancewith a difference of laser power between reproducing devices, and (ii)reproduction characteristic of a regular medium is hardly dependent onthe reproduction laser power unless the regular medium is broken or thelike.

However, different to the regular medium, there are many cases with thesuper-resolution optical information recording medium where reproductionitself is impossible unless the reproduction laser power is optimized.Different to the conventional recording film and the like, an optimumreproduction laser power differs greatly depending on a type ofreproduction layer, the reproduction layer thus causing super-resolutionreproduction by utilization of the reproduction laser power. Therefore,with the super-resolution optical information recording medium,optimization of the reproduction laser power is required to be carriedout concurrently with the optimization of the recording laser power, ina method as similar to the determination method of the aforementionedrecording laser power.

Accordingly, a test write read area is further provided in the secondarea of a recordable/reproducible super-resolution optical informationrecording medium according to an embodiment of the present invention. Inthe test write read area, (i) laser light power to be used for recordingcontents to the first area and (ii) information which adjusts the laserlight power to be used for reproducing contents in the first area arerecorded, each in a same recording density and modulation type as therecording marks to be recorded in the first area. More specifically, forexample, laser power to be used for recording is gradually raised, and aplurality of information is recorded to the write read area. Thereafter,each of the plurality of information is reproduced, while graduallyraising the laser power to be used for the reproduction. As a result, acombination of a laser power to be used for recording and a laser powerto be used for reproducing, in which a reproduction error is minimized,is obtained. That is to say, this obtained value is the optimum laserpower to be used for recording and the optimum laser power to be usedfor reproducing, for the first area. As such, an effect is attained thatinformation recording and information reproduction in the first area areappropriately carried out.

The test write read area is provided in the second area, therefore aneffect is attained that the recording laser power and the reproductionlaser power are adjusted without losing recording capacitance in thefirst area.

After information is recorded in the test write read area, the testwrite read area becomes a test read area. This is because no newinformation needs to be recorded in the test write read area, onceinformation is recorded therein.

The super-resolution optical information recording medium according tothe embodiment of the present invention, in addition to the abovearrangement, is preferably arranged such that in the second area, thetest write read area is provided at a position closer to the first areathan the pre-pits are in which the medium identification information isrecorded.

According to the arrangement, efficient information recording and/orinformation reproduction is possible. The following description explainsa reason why the efficient information recording and/or informationreproduction is possible, with reference to examples.

For example, a medium in which (i) a second area is provided at an innercircumferential part of the medium than a first area, and (ii) a testwrite read area is provided in the second area on an innercircumferential side of a pre-pit recorded with medium identificationinformation (namely, a medium in which the test write read area isprovided at a position far from the first area than the pre-pit recordedwith the medium identification information), carries out reproduction inthe following method. It is assumed that the medium already has contentsrecorded therein.

First, the reproducing device reproduces the medium identificationinformation in order to identify a type of the medium. An optical headis moved to the test write read area provided on the further innercircumferential side of the medium, whereby a test write read is carriedout. This determines recording laser power, reproduction laser power andthe like. Thereafter, again, the optical head is moved to the first areaprovided on an outer circumferential side of pre-pits in which themedium identification information is recorded, whereby contents recordedin the first area is reproduced. As such, the reproducing devicerequires the optical head to reciprocate in order to start reproduction,if the test write read area is provided in the second area at a positionfar from the first area than the pre-pits are in which the mediumidentification information is recorded. As a result, problems occur that(i) reproduction start-up time is increased, and (ii) breakage rate ofthe reproducing device caused by complex movement of the optical head isincreased.

In comparison, the optical head just requires to move in one directionif the test write read area is provided in the second area at a positioncloser to the first area than the pre-pits are in which the mediumidentification information is recorded, as in the embodiment of thepresent invention. Thereby, the optical head does not need to make anycomplex movements. Therefore, an effect is attained that reproductionstart-up time is shortened, and breakage rate of the reproducing deviceis reduced.

The above description explains a case where the test write read area isprovided closer to the first area than the pre-pits are in which themedium identification information is recorded, in a radius direction.However, it is not limited to this, and the same applies for a casewhere the test write read area is provided closer to the first area in adirection in which the pre-pits are arranged (same direction as adirection in which reproduction is carried out). The same also appliesfor the following description which describes pre-pits provided close toor far from the first area.

The super-resolution optical information recording medium according toan embodiment of the present invention is preferably arranged such that,in addition to the above arrangement, in the second area, reproductionspeed information for reproduction of the content in the first area isrecorded, by use of pre-pits that are formed by concave portions and/orprotrusions and that are not shorter than the resolution limit of theoptical system in the reproducing device; and the pre-pits in which thereproduction speed information is recorded are provided at a positionfar from the first area than the test write read area is.

According to the arrangement, a recordable/reproducible super-resolutionoptical information recording medium according to an embodiment of thepresent invention can reproduce reproduction speed information by use ofreproduction laser power optimum for a regular optical informationrecording medium.

The reproduction speed information encompass (i) so-called reproductioninformation required to obtain an analog waveform which can bedigitized, when an appropriate reproduction laser is irradiated, and(ii) digital processing information required in order to digitize ananalog waveform reproduced so as to reproduce contents and the like.

The reproduction information includes, for example, reproduction speedrange information. The reproduction speed range information isinformation for specifying reproduction speed in order to stably obtainan analog waveform based on super-resolution reproduction. This isbecause in a case where the super-resolution reproduction is possible byuse of heat, if the reproduction speed is too fast, super-resolutionreproduction is impossible because of insufficient heat, whereas if thespeed is too slow, the heat energy to be generated is too great, therebycausing damage to the medium.

The digital processing information includes, for example, reproductionclock switching information and reproduction speed switchinginformation. The reproduction clock switching information and thereproduction speed switching information are information required inorder to digitize an obtained analog waveform, when random patterns(later described in details) having different recording densities isreproduced. More details are later described.

In the embodiment of the present invention, the above arrangementallows, in the second area, determination of reproduction laser power tobe used for reproducing contents recorded in the first area, providedthat the reproduction speed information is obtained. Specifically, it ispossible to digitize an analog waveform obtained in a reproduction speedat which stable super-resolution reproduction can be attained, in astate adapted to a recording density of the test write read area.Therefore, an effect is attained that no mistakes occur in thedetermination of the reproduction laser power.

The reproduction speed denotes a linear velocity in reproduction (arelative velocity of the optical head in a reproduction positionreproducing direction, due to rotation of the medium caused by thespindle motor in order to reproduce the medium).

It is possible to appropriately digitize the analog waveform obtained ata reproduction speed at which stable super-resolution reproduction canbe attained, even in reproduction of the contents recorded in the firstarea. Therefore, it is possible to stably reproduce the contents.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the arrangement,is preferably arranged such that in the second area, recording conditioninformation for recording the content to the first area is recorded, byuse of pre-pits that are formed by concave portions and/or protrusionsand that are not shorter than the resolution limit of the optical systemin the reproducing device; and the pre-pits in which the recordingcondition information is recorded are provided at a position far fromthe first area than the test write read area is.

According to the arrangement, the recordable/reproduciblesuper-resolution optical information recording medium according to anembodiment of the present invention is capable of reproducing therecording condition information by use of reproduction power optimum fora regular optical information recording medium.

In addition, an effect is attained that a reproduction laser power canbe determined at the test write read area based on the recordingcondition information, and as a result, a determination mistake of thereproduction laser power does not occur. The recording conditioninformation includes not only the recording laser power, but alsoremoval laser power to be used for forming the recording marks, a pulsewidth and a timing of a laser, and the like.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is preferably arranged such that in the second area, areaposition information for specifying a position in the first area isrecorded, by use of pre-pits that are formed by concave portions and/orprotrusions and that have a same recording density and modulation typeas the recording marks in the first area; and the pre-pits in which thearea position information is recorded are provided at a position closerto the first area than the test write read area is.

According to the arrangement, for example, after the determination ofthe reproduction laser power, reproduction of the area positioninformation without making any changes to the determined reproductionlaser power may be carried out. This simplifies the movement of theoptical head (movement in one direction). Thus, an effect is attainedthat efficient information recording and/or information reproduction ispossible. In addition, according to the arrangement, the second area canbe made narrow, and the first area be made broad, thereby attaining aneffect that information recording capacitance is increased as a result.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is preferably arranged such that a track pitch of the firstarea is same as or narrower than a track pitch of the second area.

According to the arrangement, the recordable/reproduciblesuper-resolution optical information recording medium has a track pitchof the first area the same as or narrower than a track pitch of thesecond area.

When the track pitch of the first area and the track pitch of the secondarea are the same, it is not possible to increase the number of tracksin the first area, however an effect is attained that density ofrecorded information is increasable without providing a mechanism forchanging the track pitch. On the other hand, when the track pitch of thefirst area is made narrower than the track pitch of the second area, itis possible to increase the number of tracks in the first area.Therefore, an effect is attained that the density of the recordedinformation is further increasable. However, in order to increase thedensity, a mechanism which makes changes to the track pitch is requiredto be provided to the reproducing device.

The super-resolution optical information recording medium according toan embodiment of the present invention is preferably arranged such thatthe second area has a test read area in which pre-pits are formed byconcave portions and/or protrusions, which pre-pits adjust laser lightpower for reproducing the content in the first area, the pre-pits of thetest read area are formed in a same recording density and modulationtype as the pre-pits in the first area.

As described above, optimization of reproduction laser power isnecessary in a super-resolution optical information recording medium.

Accordingly, in a super-resolution optical information recording mediumonly for reproduction according to an embodiment of the presentinvention, a test read area is further provided in the second area ofthe super-resolution optical information recording medium, and in thetest read area, pre-pits are formed by concave portions and/orprotrusions, which pre-pits adjust laser light power for reproducing thecontent recorded in the first area. Thus, an effect is attained thatinformation reproduction is appropriately carried out in the first area.

The test read area is provided in the second area, therefore an effectis attained that reproduction laser power is adjusted without losingrecording capacitance of the first area.

The pre-pits in the test read area may be longer than a shortest pre-pitlength in the pre-pits in the first area but shorter than a longestpre-pit length in the pre-pits in the first area. This eliminates a needto carry out determination processing of the reproduction errors inorder to determine optimum reproduction power. As a result, an effect isattained that an optimum reproduction power is quickly determined, and astart-up time of a reproducing device is shortened. The reason why theoptimum reproduction power is more quickly determined due to having thepre-pits longer than the shortest pre-pit length in the pre-pits in thefirst area but shorter than the longest pre-pit length in the pre-pitsin the first area, is described in the embodiments.

The test read area is provided in the second area, therefore an effectis attained that reproduction power of the first area is quicklyadjusted.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is arranged such that in the second area, the test readarea is provided at a position closer to the first area than thepre-pits are in which the medium identification information is recorded.

According to the arrangement, efficient information recording and/orinformation reproduction is possible. The following description explainsits reason with reference to an example.

For example, a medium in which (i) a second area is provided at an innercircumferential part of the medium than the first area, and (ii) a testread area is provided in the second area on an inner circumferentialside of a pre-pit recorded with medium identification information(namely, a medium in which the test read area is provided at a positionfar from the first area than the pre-pits are in which the mediumidentification information is recorded), carries out reproduction in thefollowing method.

First, the reproducing device reproduces the medium identificationinformation in order to identify a type of the medium. An optical headis moved to the test read area provided on a further innercircumferential side of the medium, by which a test read is carried out.This determines reproduction laser power and the like. Thereafter, theoptical head is moved to the first area provided on an outercircumferential side of the pre-pits in which the medium identificationinformation is recorded, by which the content recorded in the first areais reproduced. As such, the reproducing device requires the optical headto reciprocate in order to start reproduction, if the test read area isprovided in the second area at a position far from the first area thanthe pre-pits are in which the medium identification information isrecorded. As a result, problems occur that (i) reproduction start-uptime is increased, and (ii) breakage rate of the reproducing devicecaused by complex movement of the optical head is increased.

In comparison, the optical head just requires to move in one directionif the test read area is provided in the second area at a positioncloser to the first area than the pre-pits are in which the mediumidentification information is recorded, as in the embodiment of thepresent invention. Thereby, the optical head does not need to make anycomplex movements. Therefore, an effect is attained that reproductionstart-up time is shortened, and breakage rate of the reproducing deviceis reduced.

The above description explains a case where the test read area isprovided closer to the first area than the pre-pits are in which themedium identification information is recorded, in a radius direction.However, it is not limited to this, and the same applies for a casewhere the test read area is provided closer to the first area in adirection in which the pre-pits are arranged (same direction as adirection in which reproduction is carried out). The same also appliesfor the following description which describes pre-pits provided close toor far from the first area.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is arranged such that in the second area, reproductionspeed information for reproduction of the content recorded in the firstarea is recorded, by use of pre-pits that are formed by concave portionsand/or protrusions and that are not shorter than the resolution limit ofthe optical system in the reproducing device, the pre-pits thus recordedwith the reproduction speed information are provided at a position farfrom the first area than the test read area is.

According to the arrangement, the super-resolution optical informationrecording medium only for reproduction according to an embodiment of thepresent invention is capable of reproducing the reproduction speedinformation by use of reproduction laser power optimum for a regularoptical information recording device.

The reproduction speed information encompass (i) so-called reproductioninformation required to obtain an analog waveform which can bedigitized, when an appropriate reproduction laser is irradiated, and(ii) digital processing information required in order to digitize ananalog waveform reproduced so as to reproduce contents and the like.

The reproduction information includes, for example, reproduction speedrange information. The reproduction speed range information isinformation for specifying reproduction speed in order to stably obtainan analog waveform based on super-resolution reproduction. This isbecause in a case where the super-resolution reproduction is possible byuse of heat, if the reproduction speed is too fast, super-resolutionreproduction is impossible because of insufficient heat, whereas if thespeed is too slow, the heat energy to be generated is too great, therebycausing damage to the medium.

The digital processing information includes, for example, reproductionclock switching information and reproduction speed switchinginformation. The reproduction clock switching information and thereproduction speed switching information are information required inorder to digitize an obtained analog waveform, when random patterns(later described in details) having different recording densities isreproduced. More details are later described.

In the embodiment of the present invention, the above arrangementallows, in the second area, determination of reproduction laser power tobe used for reproducing contents recorded in the first area, providedthat the reproduction speed information is obtained. Specifically, it ispossible to digitize the analog waveform obtained at a reproductionspeed at which stable super-resolution reproduction can be attained, ina state adapted to the recording density of the test read area.Therefore, an effect is attained that no mistakes occur in thedetermination of the reproduction laser power.

The reproduction speed denotes a linear velocity in reproduction (arelative velocity of the optical head in a reproduction positionreproducing direction, due to rotation of the medium caused by thespindle motor in order to reproduce the medium).

It is possible to appropriately digitize the analog waveform obtained ata reproduction speed at which stable super-resolution reproduction canbe attained, even in reproduction of the contents recorded in the firstarea. Therefore, it is possible to stably reproduce the contents.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is arranged such that in the second area, area positioninformation for specifying a position in the first area is recorded inthe second area, by use of pre-pits that are formed by concave portionsand/or protrusions and that have a same recording density and modulationtype as the recording marks in the first area, the pre-pits in which thearea position information is recorded are provided at a position closerto the first area than the test read area is.

According to the arrangement, for example, after the determination ofthe reproduction laser power, reproduction of the area positioninformation without making any changes to the determined reproductionlaser power may be carried out. This simplifies the movement of theoptical head (movement in one direction). Thus, an effect is attainedthat efficient information recording and/or information reproduction ispossible. In addition, according to the arrangement, the second area canbe made narrow, and the first area be made broad, thereby attaining aneffect that information recording capacitance is increased as a result.

A medium unique number adopted in DVD (Digital Versatile Disk) and thelike used for copy protection is different for each manufactured medium.Therefore, the medium unique number cannot be formed by compressionmolding of highly productive substrates as like the pre-pits, and isusually created by forming a groove section on the substrate by a laseror the like, at the end of manufacturing the medium.

A wavelength of a significant output laser to be used in order to createthe medium unique signal increases in cost if the wavelength is of ashort wavelength, as like one used in optical disc reproduction.Therefore, usually, the wavelength is made longer than the one used inthe optical disc reproduction (the wavelengths are long, therefore asmall groove section obviously cannot be made). In addition, since agroove section is formed by use of significant power laser, the mediumunique signal has damage in the first place. Therefore, there is a highpossibility that reproduction by use of high laser power which readilygives damage may cause reproduction deterioration of the medium uniquesignal. As such, the reproduction of the medium unique signal ispreferably carried out by use of low laser power.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the abovearrangement, is preferably arranged such that in the second area, uniquenumber presence/absence information for determining whether a uniquenumber is present or absent is recorded, by use of pre-pits that areformed by concave portions and/or protrusions and that are not shorterthan the resolution limit of the optical system in the reproducingdevice, the pre-pits in which the unique number presence/absenceinformation is recorded are provided at a position far from the firstarea than the test read area is.

According to the present embodiment, the super-resolution opticalinformation recording medium only for reproduction according to anembodiment of the present invention is capable of reproducing a mediumunique signal by use of reproduction laser power optimum for a regularoptical information recording medium, that is, low laser power.Therefore, the medium unique signal is securely reproduced. In addition,no wasteful switching of laser power is carried out. Thus, an effect isattained that efficient information recording and/or informationreproduction is possible.

The super-resolution optical information recording medium according toan embodiment of the present invention, in addition to the arrangement,is preferably arranged such that a track pitch of the first area is sameas or narrower than a track pitch of the second area.

According to the arrangement, the super-resolution optical informationrecording medium only for reproduction according to the embodiment ofthe present invention has a track pitch in the first area the same ornarrower than a track pitch of the second area.

When the track pitch of the first area and the track pitch of the secondarea are the same, it is not possible to increase the number of tracksin the first area, however an effect is attained that density of therecorded information is increasable without providing a mechanism forchanging the track pitch. On the other hand, when the track pitch of thesecond area is made narrower than the first area, it is possible toincrease the number of tracks in the first area. Therefore, an effect isattained that density of the recorded information further increasable.However, in order to increase the density, a mechanism which makeschanges to the track pitch is required to be provided to the reproducingdevice.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area is provided; and at least a recordinglayer and a super-resolution reproducing layer layered on the substratein this order, the super-resolution reproducing layer being a metaloxide film.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area is provided; and at least asuper-resolution reproduction layer and a recording layer layered on thesubstrate in this order, the super-resolution reproduction layer being ametal oxide film.

According to the arrangement, a film arrangement of arecordable/reproducible super-resolution optical information recordingmedium according to an embodiment of the present invention may be of aDVD type or a BD (Blu-ray Disc) type. Since the super-resolutionreproducing layer is a metal oxide film which has thermal resistance, aneffect is attained that reproduction durability of the super-resolutionoptical information recording medium is improved.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area and the second area are provided; andat least a reflection layer and a super-resolution reproducing layerlayered on the substrate in this order, the super-resolution reproducinglayer being a metal oxide film.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area and the second area are provided; andat least a super-resolution reproducing layer and a reflection layerlayered on the substrate in this order, the super-resolution reproducinglayer being a metal oxide film.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area and the second area are provided; andat least a light absorbing layer and a super-resolution reproducinglayer layered on the substrate in this order, the light absorbing layerabsorbing reproduction light and converting the reproduction light toheat, and the super-resolution reproducing layer being a metal oxidefilm.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably further includes: asubstrate on which the first area and the second area are provided; andat least a super-resolution reproducing layer and a light absorbinglayer layered on the substrate in this order, the light absorbing layerabsorbing reproduction light and converting the reproduction light toheat, and the super-resolution reproducing layer being a metal oxidefilm.

According to the arrangement, a film arrangement of arecordable/reproducible super-resolution optical information recordingmedium according to an embodiment of the present invention may be of aDVD type or a BD (Blu-ray Disc) type. Since the super-resolutionreproducing layer is a metal oxide film which has thermal resistance, aneffect is attained that reproduction durability of the super-resolutionoptical information recording medium is improved.

Furthermore, of the super-resolution optical information recordingmediums only for reproduction, in a case of the arrangement includingthe light absorbing layer, an effect is attained that reproductiondurability is further improved, because of a decrease in requirement ofthe super-resolution reproduction layer to absorb the reproduction laserand generate heat by the super-resolution reproduction layer itself.Even if the reproduction light power is set low, it is possible to causethe temperature to rise in order to attain the super-resolutioncharacteristic, thereby the effect is attained that electricityconsumption is reduced in reproduction.

The super-resolution optical information recording medium according toan embodiment of the present invention is preferably arranged such thatthe metal oxide film is an inorganic film which is made from titaniumoxide, cerium oxide, zinc oxide, or whose main component is titaniumoxide, cerium oxide, or zinc oxide.

According to the arrangement, the reproduction durability improves, andfurther excellent super-resolution characteristics are attained. Thus,an effect is attained that reproduction of high density recordedinformation is carried out.

The super-resolution optical information recording medium according toan embodiment of the present invention is preferably arranged such thatthe light absorbing layer is made from Si, Ge, or an alloy whose maincomponent is Si and/or Ge.

According to the arrangement, if the light absorbing layer is made fromSi, Ge, or an alloy whose main component is Si or Ge, reproductiondurability further improves, thereby attaining an effect that electricalconsumption is reduced in reproduction.

The super-resolution optical information recording medium according toan embodiment of the present invention preferably includes a heatreleasing layer for releasing the heat generated due to the irradiationof the reproduction light.

According to the arrangement, it is possible to prevent accumulation ofexcess heat generated due to the irradiation of the reproduction light.As a result, reproduction durability further improves, and a furtherhighly reliable signal reproduction is carried out.

An optical information recording medium reproducing device according toan embodiment of the present invention further preferably includes powercontrol means for controlling the reproduction light power from thereproduction means so that reproduction is carried out by use of thereproduction light power suitable for reproduction of thesuper-resolution optical information recording medium, in the case theoptical information medium is identified as the super-resolutioninformation recording medium, as a result of the identification by themedium identification means.

With this arrangement, the reproduction device is capable of accuratelyswitching the reproduction light power to a suitable reproduction lightpower in accordance with a provided optical information recordingmedium. Thus, an effect is attained such that appropriate reproductionis carried out in the reproduction of the regular optical informationrecording medium and the super-resolution optical information recordingmedium. Switching of the reproduction light power can be quickly carriedout, therefore it is possible to shorten the required amount of time forthe reproducing device to start-up.

The optical information recording medium reproducing device according toan embodiment of the present invention, in addition to the abovearrangement, is preferably arranged such that the power control meanscontrols the reproduction light power of the reproduction means based onan amplitude of a reproduction signal read out from a pre-pit in thetest read area in the super-resolution optical information recordingmedium.

Thus, in order to determine an optimum reproduction power, it is notnecessary to carry out a determination process of reproduction errorswhich is carried out in a reproduction power determination method of aconventional reproducing device. As a result, the optimum reproductionpower is quickly determined, thereby attaining the effect that astart-up time of the reproducing device is shortened.

The optical information recording medium reproducing device according toan embodiment of the present invention, in addition to the arrangement,further preferably includes clock control means for controlling areproducing clock so that the reproduction is carried out by use of areproduction clock suitable for the super-resolution optical informationrecording medium, in the case where the optical information recordingmedium is identified as the super-resolution optical informationrecording medium, as a result of the identification by the mediumidentification means.

By having the above arrangement, the reproducing device can accuratelyswitch the reproduction clock to a suitable reproduction clock inaccordance with a provided optical information recording medium,therefore reproduction can be carried out in an optimistic state whenthe regular optical information recording medium and thesuper-resolution optical information recording medium are reproduced.

A method for controlling an optical information recording mediumreproducing device according to an embodiment of the present inventionis capable of reproducing (i) the super-resolution optical informationrecording medium, and (ii) a regular optical information recordingmedium which is an optical information recording medium in whichrecording marks or pre-pits are not shorter than the resolution limit ofthe optical system, the method including: acquiring mediumidentification information by use of reproduction light power suitablefor reproduction of the regular optical information recording medium;and identifying whether or not the optical information recording mediumis a super-resolution optical information recording medium, based on themedium identification information thus acquired.

According to the method, the reproducing device can identify whether ornot the provided optical information recording medium is thesuper-resolution optical information recording medium by use of thereproduction light power suitable for the regular optical informationrecording medium, accurately and with ease.

The control means of the optical information recording mediumreproducing device may be carried out in a computer by running a controlprogram of the optical information recording medium reproducing device.Furthermore, by storing the control program of the optical informationrecording medium reproducing device in a computer-readable recordingmedium, it is possible to process the control program of the opticalinformation recording medium reproducing device on an arbitrarycomputer.

INDUSTRIAL APPLICABILITY

*207 A super-resolution medium according to the present invention isuseful for various optical discs such as optical scanning discs,magneto-optical discs, and phase-change discs, however is alsoapplicable to information recording mediums which have recording marksthat are shorter than a length of a resolution limit, such as a magneticdisc.

1-33. (canceled)
 34. An optical information recording medium, comprising: a first area in which a content is to be recorded by forming recording marks, one or more of the recording marks being shorter than a length of a resolution limit of an optical system in a reproducing device; and a second area in which medium identification information for specifying a type of the medium and information regarding reproduction speed for reproduction of the content in the first area of the optical information recording medium are recorded by use of concave portions and/or protrusions that are not shorter than the resolution limit of the optical system, the content in the first area being recorded with (1, 7) RLL modulation.
 35. An optical information recording medium, comprising: a first area in which a content is recorded by use of concave portions and/or protrusions, one or more of the concave portions and/or protrusions being shorter than a length of a resolution limit of an optical system in a reproducing device; and a second area in which medium identification information for specifying a type of the medium and information regarding reproduction speed for reproduction of the content in the first area of the optical information recording medium are recorded by use of concave portions and/or protrusions that are not shorter than the resolution limit of the optical system, the content in the first area being recorded with (1, 7) RLL modulation.
 36. A method for recording a content in an optical information recording medium, the optical information recording medium comprising: a first area in which a content is to be recorded by forming recording marks, one or more of the recording marks being shorter than a length of a resolution limit of an optical system in a reproducing device; and a second area in which medium identification information for specifying a type of the medium and information regarding reproduction speed for reproduction of the content in the first area of the optical information recording medium are recorded by use of concave portions and/or protrusions that are not shorter than the resolution limit of the optical system, the method comprising the step of recording the content in the first area with (1, 7) RLL modulation. 